fluent's "outflow" BC not compatible with Singhal cavitation model?

aditya.pandare · January 31, 2013, 00:26

Hi,
I am simulating a cavitating flow in fluent 14.5 and trying to use the Singhal et al cavitation model for the same.
Due to the peculiar flow conditions, I have to use the "outflow" BC at the outlet.
but when I try to run the Singhal model with outflow, it gives 2 errors:
1. outflow cannot be used with cavitation model
2. divergence detected in AMG solver ( all the eqns: k, e, x,y,z momentum, pressure correction)

but I can run the same simulation with Schnerr-sauer cavitation model

so is it the case that only the Singhal cavitation model is not compatible with "outflow"? or is there something wrong with my case setup?

any help will be useful!
thank you

sarodesr · October 24, 2013, 08:27

Hi,

Just wondering how did you use Singhal Model in fluent v 14.5. As per my observation, in cavitation model only two models are shown by fluent 1) Schnerr-sauer 2) Zwart-geber-Blmari.
I tried to search but didn't find. Did you write UDF/UDS for the same.

regards,
Sarang

Kokemoor · October 24, 2013, 10:16

My limited experience with the Singhal et al model found it to be very unstable and sensitive to mesh and initialization. It may simply take some patience and experimentation to find the right conditions for convergence.

I'm not sure why your outflow condition might work with Schnerr-Sauer. The Fluent User's Guide says under 6.3.10 that outflow can't be used with any multiphase models (presumably because the mass balance correction doesn't work with multiple phases).

aditya.pandare · October 24, 2013, 13:16

Sarang, after you select the Multiphase model in the models tab, use "solve/set/expert" in the text command window. enable the Singhal cavitation model.

Kokemoor, yes you are right. actually I found this out long back, but forgot to update here; thanks anyways.

January 31, 2013, 00:26	fluent's "outflow" BC not compatible with Singhal cavitation model?	#1
aditya.pandare New Member Aditya Pandare Join Date: Aug 2012 Location: Pune, India Posts: 20 Rep Power: 13	Hi, I am simulating a cavitating flow in fluent 14.5 and trying to use the Singhal et al cavitation model for the same. Due to the peculiar flow conditions, I have to use the "outflow" BC at the outlet. but when I try to run the Singhal model with outflow, it gives 2 errors: 1. outflow cannot be used with cavitation model 2. divergence detected in AMG solver ( all the eqns: k, e, x,y,z momentum, pressure correction) but I can run the same simulation with Schnerr-sauer cavitation model so is it the case that only the Singhal cavitation model is not compatible with "outflow"? or is there something wrong with my case setup? any help will be useful! thank you

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October 24, 2013, 08:27		#2
sarodesr New Member Sarang Join Date: Jul 2013 Posts: 12 Rep Power: 12	Hi, Just wondering how did you use Singhal Model in fluent v 14.5. As per my observation, in cavitation model only two models are shown by fluent 1) Schnerr-sauer 2) Zwart-geber-Blmari. I tried to search but didn't find. Did you write UDF/UDS for the same. regards, Sarang

October 24, 2013, 10:16		#3
Kokemoor Senior Member Andrew Kokemoor Join Date: Aug 2013 Posts: 122 Rep Power: 13	My limited experience with the Singhal et al model found it to be very unstable and sensitive to mesh and initialization. It may simply take some patience and experimentation to find the right conditions for convergence. I'm not sure why your outflow condition might work with Schnerr-Sauer. The Fluent User's Guide says under 6.3.10 that outflow can't be used with any multiphase models (presumably because the mass balance correction doesn't work with multiple phases).

October 24, 2013, 13:16		#4
aditya.pandare New Member Aditya Pandare Join Date: Aug 2012 Location: Pune, India Posts: 20 Rep Power: 13	Sarang, after you select the Multiphase model in the models tab, use "solve/set/expert" in the text command window. enable the Singhal cavitation model. Kokemoor, yes you are right. actually I found this out long back, but forgot to update here; thanks anyways.